Yeah, I tried to hold it so that it would be as far from the bottom as it could be, but also still be about where the minimum water level line would be too. It's just a taller heater. If it were able to be installed sideways it would be perfect!

I want to update on my 2nd heater that I got. It's a 50W and I put it in my 5 gallon with the babies. It works just as consistently as the 25W one, never varies a single degree in temperature. Even though it's only 64F in my house right now I can go to bed and wake up and it will be the exact same temperature - and it gets cold in here at night now! Only issue is, it's off by exactly 3 degrees. It's probably just this particular unit I have as I really believe that they have excellent quality products. I plan on keeping it and using it for as long as I can - it has a 3 year warranty so as long as it keeps holding the temperature consistent, I'll keep it in use.

Also, I still haven't heard anything back from my inquiry to them about why they can't be installed sideways. I'll definitely post again when I do :)